The present invention relates to slip prevention particle injection devices which are installed in the vicinity of wheels of railway rolling stock and spread particles for preventing slippage of the wheels.
Rain or snow may cause slippage of wheels of railway rolling stock traveling at a high speed on rails. Indeed, wetting of the rails with rain or accumulation of snow thereon causes such effects as the decrease in tacking coefficient between the wheels and the rails, idle rotation of the wheels, decrease in traveling speed, and inability to reach the preset traveling speed. Furthermore, when brakes are applied to stop the railway rolling stock, it cannot be stopped in a predetermined stoppage position due to slippage of wheels and the stoppage time required to stop the railway rolling stock after the application of brakes is extended.
In order to resolve those problems, sand has been sprinkled between the wheels and the rails to prevent the slippage of the wheels. The conventional sand sprinkling devices had a simple structure composed of a tank for retaining the sand and a guiding duct for dropping the sand. Since the sand sprinkling mechanism was based on the sand falling under gravity, the sand was scattered by the wind pressure created by the traveling railway rolling stock and the sand was difficult to sprinkle accurately at the appropriate location between the wheels and rails.
Recently, the conventional sand sprinkling devices have been improved and a device spraying the sand by a jet has been developed.
Japanese Utility Model Application Laid-open No. S56-18203 disclosed a sand sprinkling device for railway rolling stock comprising a sand box retaining the sand, a sand sprinkling duct connected to the sand box, an air duct for feeding the air to the sand sprinkling duct, and an air duct for feeding the air to the sand box. In such a device, the sand retained in the sand box is introduced into the sand sprinkling duct by a suction force created by the compressed air fed into the sand sprinkling duct, and the sand is injected between the wheels and the rails by the compressed air.
Japanese Patent Application Laid-open No. S62-77204 disclosed a particle injector device for railway rolling stocks, comprising a particle supply duct for supplying particles such as sand and the like, a compressed air supply duct for supplying the compressed air, a mixing chamber connected to the particle supply duct and compressed air supply duct, and an injector duct connected to the mixing chamber and having an injection opening. In such a device, the compressed air supplied from the compressed air supply duct is mixed in the mixing chamber with the particles supplied from the particle supply duct and the particles together with compressed air are injected between the wheels and rails from the injection opening of the injector duct.
Japanese Examined Patent Application No. H5-14673 disclosed a particle injector device for railway rolling stock comprising a retainer tank for retaining particles such as sand and the like, a retainer chamber connected to the retainer tank via a transportation pipe, a particle supply duct connected to the retainer chamber, and a compressed air supply duct connected to an air supply duct. In this device, the compressed air is fed to the compressed air supply duct via the air supply duct, a suction force is generated in the vicinity of the outlet of the particle supply duct by the flow of compressed air, thereby introducing the particles present in the retainer chamber into the particle supply duct and injecting the particles together with the compressed air between the wheels and rails from the particle supply duct.
All of the devices described in the Japanese Utility Model Application Laid-open No. S56-18203, Japanese Patent Application Laid-open No. S62-77204, and Japanese Examined Patent Application No. H5-14673 comprise an injector duct for injecting the particles and have a structure in which compressed air is fed into the injector duct, the particles are mixed with the compressed air, and the particles are injected together with the compressed air between the wheels and rails. The drawback of all of the devices is in that the injected quantity of the particles is difficult to adjust.
Thus, the injection pressure has to be increased when the particles do not get in the appropriate location between the wheels and rails because of the wind or turbulent air flow generated in the vicinity of wheels of traveling railway rolling stock. However, the drawback of the conventional device is that the injected quantity is increased if the injection pressure is raised and the flow rate of compressed air is increased. The excessive injection of particles causes unnecessary consumption of particles and the cost of slippage prevention rises. Moreover, when the excessively sprinkled particles penetrate into a point gap, they make it impossible to operate the point or produce a negative effect on a signal circuit. Another drawback of the conventional devices is that if the compressed air quantity is adjusted so that the injected quantity does not become too high, the prescribed injection pressure cannot be obtained and the particles cannot be accurately injected at the target location between the wheels and rails.
Thus, when an attempt was made to inject the particles accurately at the target location under the prescribed injection pressure, the injected quantity became too high. On the other hand, when the compressed air quantity was adjusted so as to control the injected quantity to the appropriate level, the injection pressure was insufficient, the particles were not injected at the target location, and the adjustment of the injected quantity of particles was difficult.
Japanese Unexamined Patent Application No. H4-310464 disclosed a particle injector device for railway rolling stock comprising a tank retaining the particles, a mixing apparatus connected to the particle retainer tank, an air duct for feeding compressed air to the particle retainer tank, an air duct which is a branch of the aforesaid air duct and serves to feed compressed air into the mixing apparatus, a control apparatus for controlling the quantity of particles introduced from the particle retainer tank into the mixing apparatus, an injector duct connected to the mixing apparatus, and a pinch valve for adjusting the injected quantity. In such apparatus, particles are introduced into the mixing apparatus from the tank in which the pressure is increased by the compressed air, the particles are mixed with the compressed air inside the mixing apparatus, and the particles are injected together with compressed air between the wheels and rails from the injection opening of the injector duct. In this case, the quantity of particles introduced into the mixing chamber from the tank is adjusted to the prescribed quantity by the control apparatus. Furthermore, the injected quantity from the injector duct is adjusted by the pinch valve.
The device disclosed in Japanese Unexamined Patent Application No. H4-310464 adjusts the injected quantity of particles, but the device requires a plurality of control apparatuses and an accordingly large number of electric wirings and has a complex structure. The slip prevention particle injection devices of this type are typically installed in the vicinity of wheels, in other words, so that they are exposed to the outside. Therefore, the materials thereof are subjected to corrosion or degradation. As a result, the control apparatus can malfunction or the electric wiring system can be damaged. For those reasons, there is a need for slip prevention particle injection devices which have a simple structure.
Accordingly, the inventors have conducted an intensive study aimed at the development of an injector device in which compressed air is fed into a particle retainer tank and a mixing chamber, pressure inside the tank is increased by the compressed air, particles are fed out into the mixing chamber by the respective pushing force, the particles are mixed with the compressed air in the mixing chamber, and the prescribed quantity of particles are injected from an injector duct together with the compressed air, without providing a mechanism for electric control of the injected quantity. In the course of the study, the inventors have set the following tasks.
The first task is associated with the difficulty of adjusting the injected quantity of particles. The structure in which a pressure is applied inside the tank by compressed air and the particles present in the tank are fed out into the mixing chamber by the respective pushing force essentially cannot resolve the above-described problem of injected quantity adjustment. Thus, the following problems were involved: if the particles are injected by the prescribed injection pressure, the injected quantity becomes too large, and, conversely, if the injected quantity is adjusted to an appropriate level, the injection pressure necessary for spraying the particles cannot be obtained and the particles cannot be sprayed at the target location.
The second task is associated with the movement of particles under the effect of residual pressure inside the tank when the particle spraying operation is terminated.
In a structure comprising no mechanism for controlling the injected quantity, no on-off valve is installed in the passage connecting the mixing chamber and the injector duct and the passage remains open. However, when the particle spraying operation is terminated, the air flow passage through which compressed air is supplied is closed and the supply of compressed air into the particle retainer tank and mixing chamber is terminated. In this case, because of the residual pressure inside the tank, the particles located inside the tank are pushed by this residual pressure and, as a result, the particles are fed out into the mixing chamber. The particles that were fed out into the mixing chamber flow into the injector duct and stay inside the injector duct and in the vicinity of the nozzle. The residual pressure is not sufficient to inject the particles from the injector duct to the outside.
If the particle spraying operation is resumed, the air passage is opened and compressed air is fed to the tank and mixing chamber. However, in this case, the initial air pressure does not provide a force necessary to inject the particles that stayed inside the injector duct at the target location between the wheels and rails. As a result, a situation is created in which rather large particle aggregates fall onto the rails from the nozzle under gravity. It means that the spraying of particles cannot be conducted in a stationary state immediately after the particle spraying operation has been restarted. Thus, in this case, the particles flowing out of the injector duct immediately after the particle spraying operation has been restarted are not injected at the target location between the wheels and rails and therefore make no contribution to slippage prevention and are consumed uselessly.
Furthermore, on the rainy or snowy days, water penetrates into the nozzle of the injector duct, particles that stayed in the vicinity of the nozzle of the injector duct are wetted with water, forming a solid mass and filling and clogging the nozzle.
With the foregoing in view, it is an object of the present invention to provide a slip prevention particle injection device in which the injected quantity of particles can be adjusted to an appropriate level with a simple structure.
Another object of the present invention is to provide a slip prevention particle injection device in which particles present in the tank are prevented from being fed into the injector duct and from staying therein when the particle spraying operation is terminated.
Still another object of the present invention is to provide a slip prevention particle injection device which has a low production cost, decreased particle consumption, and very good cost efficiency.
The particle retainer tank retains a preset quantity of particles for preventing slippage, and an air through-flow duct is provided inside the tank. An air supply duct for supplying compressed air is connected to the air through-flow duct. An air inflow duct is provided so as to be connected to the air through-flow duct in a state in which one end thereof is opened in the tank. The compressed air supplied from the air supply duct flows through the air through-flow duct and into the air inflow duct which is a branch of the air through-flow duct. The air inflow duct is preferably provided inside the tank. Air flow rate adjustment means for adjusting the flow rate of compressed air can be provided in the air inflow duct.
A smaller-diameter air passage section formed by narrowing the air passage is provided in the air through-flow duct. The position where the smaller-diameter air passage section is provided is preferably in the vicinity of the connection section connecting the air through-flow duct and air inflow duct. Further, a mixing chamber where the particles are mixed with compressed air is provided in the air through-flow duct. The particle introduction hole for introducing particles into the mixing chamber is also provided; this particle introduction hole is preferably provided directly in the mixing chamber.
One end of the air discharge duct is provided so as to be connected to the air through-flow duct in a state in which it is open inside the tank. The air through-flow duct is preferably provided inside the tank. When the air through-flow duct is provided inside the tank, the connection section of the air through-flow duct and air discharge duct is provided in a location at the outlet side of the air through-flow duct beyond the mixing chamber. An injector duct is connected to the outlet side of the air through-flow duct, and a nozzle is provided at the tip of the injector duct.
It is preferred that an observation window be provided in the tank to check visually the quantity of particles retained in the tank.
The configuration of the device in accordance with the present invention is such that the air through-flow duct and air inflow duct are provided and the supply of compressed air is branched into the air through-flow duct and air inflow duct. Moreover, a smaller-diameter air passage section is provided in the air through-flow duct. Therefore, the quantity of compressed air flowing into the mixing chamber can be made less than the quantity of compressed air flowing into the air inflow duct. As a result, the quantity of particles introduced into the mixing chamber from the particle introduction hole by the negative pressure generated in the mixing chamber is also adjusted to an appropriate quantity and excessive quantity of particles is not introduced therein.
On the other hand, compressed air branched out of the air through-flow duct and flowing in the air inflow duct is supplied into the tank and increases pressure therein. However, a portion of the compressed air that has flown into the tank flows out into the air through-flow duct via the air discharge duct. As a result, a high internal pressure corresponding to the quantity of compressed air supplied into the tank is not formed. Therefore, the pressure inside the tank does not create a pushing force sufficient to introduce the excessive quantity of particles from the particle introduction hole into the mixing chamber. Therefore, the appropriate quantity of particles is introduced into the mixing chamber. Since the entire quantity of compressed air flowing in the air through-flow duct, air inflow duct, and air discharge duct is used for particle injection, the particles can be injected under the preset injection pressure.
Thus, in accordance with the present invention, the injected quantity of particles can be adjusted to an appropriate quantity, without becoming excessive during particle spraying, and the unnecessary consumption of particles can be prevented. Preventing the excessive injected quantity makes it possible to resolve the conventional problems such as the introduction of excessively sprinkled particles into a point gap, which disables the point, and a negative effect produced on a signal circuit.
Furthermore, providing means for adjusting the air flow rate in an air inflow duct makes it possible to adjust the flow rate of compressed air supplied into the tank and therefore to change, as necessary, the injected quantity of particles.
In accordance with the present invention, when the particle spraying operation is terminated, the air present inside the tank flows via the air discharge duct into the air through-flow duct and then from the air through-flow duct into the injector duct from which it is released into the atmosphere. Therefore, the residual pressure inside the tank is rapidly decreased and the occurrence of situation in which the residual pressure inside the tank introduces the particles into the mixing chamber, moves them into the injector duct, and causes them to stay inside the injector duct and in the vicinity of the nozzle can be prevented. As a result, in accordance with the present invention, when the particle spraying operation is restarted, particle injection in a stationary state can be conducted immediately after the operation has been restarted, so that a large quantity of staying particles are not pushed out from the injector duct and nozzle and do not fall on the rails.
Furthermore, as described above, since the particles do not stay in the vicinity of the nozzle when the particle spraying operation is terminated, there is no danger that water will permeate from the nozzle and harden the particles into a mass, thereby clogging the nozzle.
The injector device in accordance with the present invention has a simple structure. Therefore, the production cost is low. Moreover, since the consumption of particles is decreased, the cost of preventing slippage is reduced and the device has a very high cost efficiency.